Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net Income	$ 47,263	$ 138,577	$ 113,989
Other Comprehensive Income (Loss), net of tax:
Net change in unrealized gains (losses) on marketable Securities, net of deferred tax (expense) benefit of $120, $7,427 and $(5,223) for the years ended December 31, 2012, 2011 and 2010, respectively	(187)	(13,004)	8,700
Reclassification adjustments for amounts included in net income, net of deferred tax (expense) benefit of $(86), $389 and $598 for the years ended December 31, 2012, 2011 and 2010, respectively	135	(688)	(999)
Defined benefit plan adjustments	(1,952)
Foreign currency translation	170	(154)	1,394
Other Comprehensive Income (Loss), net of tax	(1,834)	(13,846)	9,095
Comprehensive Income, net of tax	$ 45,429	$ 124,731	$ 123,084